Reduce WAL directory configuration to one variable
Reduce WAL directory configuration to one variable

This eliminates the need to warn the user about one or the other not
being set.

Issue: [ch6688]

the1forte/crunchy-containers,the1forte/crunchy-containers,CrunchyData/crunchy-containers,the1forte/crunchy-containers,CrunchyData/crunchy-containers,CrunchyData/crunchy-containers